Bugzilla – Bug 1221554
VUL-0: CVE-2021-47125: kernel: sch_htb: fix refcount leak in htb_parent_to_leaf_offload
Last modified: 2024-06-05 12:56:43 UTC
In the Linux kernel, the following vulnerability has been resolved: sch_htb: fix refcount leak in htb_parent_to_leaf_offload The commit ae81feb7338c ("sch_htb: fix null pointer dereference on a null new_q") fixes a NULL pointer dereference bug, but it is not correct. Because htb_graft_helper properly handles the case when new_q is NULL, and after the previous patch by skipping this call which creates an inconsistency : dev_queue->qdisc will still point to the old qdisc, but cl->parent->leaf.q will point to the new one (which will be noop_qdisc, because new_q was NULL). The code is based on an assumption that these two pointers are the same, so it can lead to refcount leaks. The correct fix is to add a NULL pointer check to protect qdisc_refcount_inc inside htb_parent_to_leaf_offload. References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-47125 https://git.kernel.org/stable/c/944d671d5faa0d78980a3da5c0f04960ef1ad893 https://www.cve.org/CVERecord?id=CVE-2021-47125 https://git.kernel.org/stable/c/2411c02d03892a5057499f8102d0cc1e0f852416 https://bugzilla.redhat.com/show_bug.cgi?id=2269839
Offending commit (ae81feb7338c) found in: - ALP-current - cve/linux-5.14 - SLE15-SP4-LTSS - SLE15-SP5 - SLE15-SP6 - stable Fixing commit (944d671d5faa) found in: - ALP-current - cve/linux-5.14 - SLE15-SP4-LTSS - SLE15-SP5 - SLE15-SP6 - stable All branches fixed, @kernel-team please add the reference.
All done, closing.